Not, like, doing something you don't like, i.e murder or picking their nose. Just opinions -- thoughts. They may act on them, but assume for the question that it's all in your and their heads.

This can be as simple as them liking a food you don't. Do you think less of their character/person because of this? Probably not. It's just food.

Or it could be something more serious, like a political or religious difference. Saw you're a liberal, and someone else thinks conservative political ideals are better. Or, you're an atheist and someone else is religious. Do you think less of them because of these differences?

Or it could be something that has ever greater impact, like someone thinking that black people are lazy, shiftless criminals or nuclear war is a good idea, and you disagree.

Where do you draw the line? Why? Is there even a line to be drawn? How is your opinion of them influenced by their opinions? Conversely, is your opinion of people changed if they have opinions that agree with yours? Why do you think this is? Is it a good thing?